Re: Bug: fstenv is wrongly implemented

[Paolo Bonzini]

On 02/04/21 10:29, Ziqiao Kong wrote:
> According to git blame, this bug is introduced about 13 years ago:
> https://github.com/qemu/qemu/blame/633decd71119a4293e5e53e6059026c517a8bef0/target-i386/fpu_helper.c#L997.
>
> We also had a patch for this bug:
> https://github.com/unicorn-engine/unicorn/commit/59b09a71bfc6fd8b95357944f6be9aa54f424421
> which you may refer to. I can also help draft a patch if necessary.

Hi!

Unfortunately the patch is incorrect, because fpu_update_ip is called 
only at translation time and not at run-time.  If more than one x87 
instruction is present in the same translation block, or if a 
translation block has been compiled after the one that is executing, 
env->fpip will be incorrect.

Thanks,

Paolo